Ravenous Colorado potato beetles are torpedoing the cultivation of potatoes and other crops worldwide. Ingenious survival strategies of the imported leaf beetles make combating them a special challenge for natural hobby gardeners. Find out important details about the insatiable enemy in the potato patch in the profile. This guide explains how to fight Colorado potato beetles naturally with practical tips and tricks.

Colorado potato beetles are a very stubborn pest

Table of Contents

Show all
  1. the essentials in brief
  2. Profile and life cycle
  3. Devastating image
  4. Fight potato beetles
  5. Combat potato beetles naturally
  6. Home remedies for potato beetle
  7. Organic spray against potato beetles
  8. Plants against Colorado potato beetle
  9. Prevent potato beetle
  10. frequently asked Questions

    11. the essentials in brief

    • The third and fourth instar Colorado potato beetle larvae cause the worst damage in the vegetable garden.
    • Colorado potato beetles are 7-15 cm in size with light yellow elytra with black stripes. Larvae are bright red, later turning orange-yellow with black spots.
    • Natural remedies against Colorado potato beetles are neem oil, tansy tea, rock flour, (14.13€) coffee grounds, nettle manure and manual collection.

    Colorado potato beetle - profile and life cycle

    The Colorado potato beetle originally comes from North America

    The year 1877 has burned itself into the collective memory of commercial and private potato farmers. In that year the first potato beetles were sighted in Germany, Holland and England. Within a few years, the beetles became the most dangerous pests for growing potatoes and other nightshades. Colorado potato beetles wreak such catastrophic devastation that they were even considered as a biological weapon in the middle of the last century.

    In order to emerge victorious from confrontations with the Colorado potato beetle as a hobby gardener, you should be familiar with the appearance and habits of the voracious beetles and insatiable larvae. The following profile provides you with brief and compact information about all the important aspects:

    • Insect Family: Leaf Beetles (Chrysomelidae)
    • Beetle species: Colorado potato beetle, potato beetle, Colorado beetle (Leptinotarsa decemlineata)
    • Origin: North America, specifically the state of Colorado
    • Body length of adult beetles: 7-15 mm
    • Appearance: Roundish-oval, light yellow elytra with 10 dark brown or black longitudinal stripes
    • Appearance Larvae: blood-red, later orange-red, black spots on the sides and on the head
    • Appearance eggs: cylindrical shape, orange-yellow in color
    • Occurrence per year: 1 to 3 generations
    • Activity: diurnal
    • Lifespan: 2 years with one hibernation
    • Food plants: Solanaceae, primarily potatoes, tomatoes, peppers, aubergines

    The conspicuous alert behavior of Colorado potato beetles has a solid reason. When danger threatens, the beetles excrete a poisonous defense secretion to keep enemies at bay. The toxin is harmless to humans. Of course, birds, toads and other beneficial creatures could find it difficult to stomach. The images below illustrate the unmistakable appearance of the Colorado potato beetle and Colorado potato beetle larva.

    Consequential life cycle

    For successful control, it is important to know the life cycle of Colorado potato beetles. The actual causes of the catastrophic crop damage are the voracious larvae in the last two stages of development. A brief foray into the life of a Colorado potato beetle illustrates its ingenious survival strategy, which is causing frustration among hobby gardeners and farmers worldwide.

    When the first potato plants sprout in spring, the Colorado potato beetle wakes up in its winter quarters deep in the ground. As soon as the beetles have rubbed their hibernation out of their eyes, they devote themselves to feeding on the tender leaves. By the end of May/beginning of June, the adult Colorado beetles have strengthened enough to start breeding. Mating females lay their eggs in batches on the underside of the leaves. In one summer, a busy female will lay up to 1200 eggs in packages of 20 to 80 pieces. Given a two-year lifespan, a single female Colorado potato beetle produces up to 2400 offspring.

    Bright red larvae hatch from the eggs within 5 to 12 days and immediately attack the leaves. Now we're getting one after the other. The larvae grow rapidly over the course of a total of four stages of development. At the same time, her craving for potato leaves increases steadily and takes on disastrous dimensions in the last phase. After 17 to 20 days the spook is over, because the eating machines crawl into the ground to pupate.

    Pupation and hatching in the soil take about two weeks. The vicious circle then starts all over again, with the fully grown Colorado potato beetles flying out, eating the leaves and giving birth to the second generation in July. Under ideal conditions, a third generation develops in August and finishes off the few surviving potato plants. The beetles of this year's generations overwinter at a depth of up to 50 centimeters in the garden soil.

    Devastating image

    If the infestation is not combated, Colorado potato beetles cause great damage

    The spiral of extermination begins when Colorado potato beetles crawl out of the ground after winter. With each development step, the damage in the vegetable garden escalates. The following overview of the damage pattern makes it clear why timely intervention plays a key role in the fight against potato beetles:

    1. Maturation feeding until oviposition: slight feeding damage on the leaf edges
    2. First and second larval stage: moderate damage as edge and pitting damage on nightshade plants
    3. Third and fourth larval stage: continuous defoliation until affected plants are completely skeletonized

    Potato plants are the primary source of food, to which the name of the pest refers. In the absence of their favorite plants, Colorado potato beetles do not spurn other nightshade plants. These include tomatoes, peppers, aubergines and chili.

    digression

    Ladybugs eat Colorado potato beetle eggs

    If ladybirds are present in the vegetable garden, the risk of infestation by Colorado potato beetles drops noticeably. Although adult beetles are well protected from enemies by their warning clothing, this advantage only applies to the brood to a limited extent. [ladybird larvae]Ladybird larvae[/link] like to eat the Colorado potato beetle's eggs. Because ladybugs start their family planning as early as the end of April, an armada of hungry larvae await the start of the Colorado potato beetle's oviposition in June. In order for the preventive strategy to bear fruit, you can increase the population of ladybugs in a targeted manner. Certified breeding farms supply you with hard-working larvae of the local two-spot ladybird together with an organic box for animal-friendly spreading in the potato patch.

    Fighting Colorado potato beetles - methods at a glance

    In the first and second instar, a Colorado potato beetle larva is particularly susceptible to control measures. Furthermore, the brood is not yet driven by an insatiable hunger, as in later stages of development. If the right remedies are used at the perfect time, the big third and fourth instar feasting in your yard won't happen. The following table names proven remedies against Colorado potato beetles:

    Natural Methods home remedies organic spray defense plants
    collect coffee grounds neem oil linen
    nettle manure moonmin Tansy Tea Nasturtium
    mint broth wood ash horseradish
    rock flour

    Chemical sprays are not included in this overview for two important reasons. If you fight Colorado potato beetles chemically, it cannot be ruled out that your potatoes are contaminated with the insecticide. To avoid this same problem, home gardeners invest a lot of time and effort in growing vegetables naturally. Furthermore, Colorado potato beetles and larvae have developed a pronounced resistance to pesticides. Even highly toxic sprays, such as DDT in the post-war years and pyrethrum in the 1970s, had shot their powder within a short time in the fight against the Colorado potato beetle plague.

    Combat potato beetles naturally

    In the struggle with the Colorado potato beetle, hobby gardeners give preference to natural means. The focus is on four methods that have proven themselves in garden practice. The exact procedure is explained in the following sections.

    collect

    Collecting is tedious but effective

    In the allotment garden, manual control of Colorado potato beetles, larvae and eggs cannot be topped in terms of effectiveness. Since the traditional method is associated with a great deal of time and effort, small areas of cultivation are primarily suitable for collecting the pests. How to do it right:

    • Best time: repeating at regular intervals from May until August
    • Best time of day: early morning hours
    • First step: shake plants, collect fallen Colorado potato beetle and larvae
    • Step Two: Examine top and bottom of leaves to crush eggs and egg packets by hand

    Manual control raises the question for natural hobby gardeners: collecting Colorado potato beetles and then? Unfortunately there is only one answer to this. Colorado potato beetles are on the black list of invasive species, the so-called neophytes. Thus, the beetles move on an equal footing with brown rats, nudibranchs, mosquitoes and other creatures that are feared as biological invaders. It is forbidden to simply release neophytes because they cause distress to native species. A tried and tested, gentle method is to throw collected Colorado potato beetles in a glass with water.

    nettle manure

    Organic gardeners attest to the best effectiveness against Colorado potato beetles of nettle manure that they produce themselves. If the natural product is used regularly from spring, it strengthens the resistance of young potato plants to pests. Timely spraying of leaves spoils the plan of bold females to place their eggs on them. How to do it:

    1. Layer 1 kg of fresh nettle in a wooden tub
    2. Pour 10 liters of collected rainwater over it
    3. Cover container with chicken wire
    4. Stir several times a day with a wooden stick

    The fermentation process takes 10 to 14 days. Strain the finished nettle manure. In this state the manure is too concentrated for plants. Before using as a natural remedy against Colorado potato beetles, dilute one liter of nettle manure with 8 to 10 liters of water. The important thing to remember is that you spray the tops and bottoms of potato and tomato plants at least once a week.

    mint broth

    Peppermint tea helps against young potato beetles

    Mint broth has gained a good reputation as an immediate measure against tiny Colorado potato beetle larvae shortly after hatching. In order not to let the waiting time for finished nettle manure go by unused, tackle the pests with freshly brewed peppermint tea. It is important to note that you are using real peppermint (Mentha x piperita) and not a cultivated mint variety such as pineapple mint or strawberry mint.

    rock flour

    If there is a wafer-thin layer of rock dust on the leaves, Colorado potato beetles will flee. You should therefore regularly pollinate the leaves above and below so that no eggs and larvae can settle here. Begin as soon as growth begins, ideally before the pests emerge from the soil. A positive side effect: Rock flour also effectively prevents aphids.

    Fighting Colorado potato beetles naturally aims to significantly reduce the infestation. Scattered specimens will always elude the means. Your potato plants can live well with it and still give you a rich harvest.

    Home remedies for potato beetle

    The home remedies in the table above take the fright out of a Colorado potato beetle plague when it encounters the larvae of the first and second stages. Applied early, plant leaves are primed for invasion by egg-packed beetle females. The following three home remedies ward off potato beetles:

    coffee grounds

    Coffee is not only a great fertilizer, it also helps against potato beetles

    With every cup of freshly brewed coffee, you also produce a powerful natural remedy against gorged Colorado potato beetle larvae. How to use the home remedy correctly:

    1. Pour the coffee grounds from the filter onto a plate or into a sieve
    2. Leave to dry for 1 to 2 days
    3. Scatter on the ground from the beginning/middle of May
    4. from a growth height of 10 cm, dust the plant leaves thinly (upper and lower sides)
    5. Repeat treatment at 4 week intervals

    You should not use the home remedy in the vegetable patch at shorter intervals. Coffee grounds have the property of lowering the pH value in the garden soil in large quantities.

    moonmin

    If you are looking for an inexpensive alternative to rock flour, you will find it on the kitchen shelf. The extremely fine Mondamin powder is just as successful in repelling Colorado potato beetles and Colorado potato beetle larvae. Apply the household remedy with a powder spray when the plant leaves are still damp from the dew in the early morning and Moonminum is sticking well.

    wood ash

    Hobby gardeners with their own fireplace or grill oven swear by wood ash as a natural fertilizer. Less well known is an excellent home remedy against Colorado potato beetles. In order for wood ash to do its job perfectly, it must not contain any toxic residues, for example from varnished wood or glossy magazines. If female Colorado potato beetles with eggs in their luggage come across plant leaves with a thin layer of wood ash, they turn away in disgust. If the ashes settle on active larvae, it has been proven that the rabble lose their appetite.

    Coffee grounds, lunar amine and wood ash are lost as the only means of combating this. In combination with natural methods, on the other hand, unexpected synergy effects unfold. A good example is treating endangered plants with nettle manure. As soon as the liquid has dried on the leaves, the second wave follows in the form of moonminus or wood ash.

    tips

    Next time you prune a thuja, please don't throw away the clippings. Prepare a tea from the tree of life shoots. Repeatedly spray endangered plants with this decoction.

    Biological sprays against Colorado potato beetles

    Effective sprays against Colorado potato beetles can be made from neem oil or tansy

    Two biological sprays have so far been able to get at hardened potato beetles. A bio-insecticide is thanks to modern research. The alternative was already used in the 19th century as a tried and tested means of combating the dreaded pests and, surprisingly, has not lost any of its effectiveness to this day. Read the details below:

    neem oil

    A magnificent tree thrives in the tropical regions of the world, the fruits of which are bulging with much sought-after seeds. Neem oil, a biological insecticide against Colorado potato beetles, is extracted from these seeds. The natural ingredients do not have an immediate lethal effect on the pests. Rather, growth, reproduction and food intake are inhibited. The following products with neem oil as the main ingredient enjoy good ratings from bug-plagued hobby gardeners:

    • Bayer Garden Organic Pest Free Neem
    • Compo Bio Insect Free Neem
    • Neudorff Neem Plus Pest Free
    • Natures Organic Pest Free Neem

    The best time to apply is within the first five days after the eggs are laid, ideally exactly on the fifth day. To determine the exact date, please check the top and bottom of the leaves of nightshade plants every day. It's good to have a magnifying glass with you so the tiny eggs don't escape your attention.

    Tansy Tea

    Ask an experienced organic plant doctor: What helps against Colorado potato beetles? The answer came like a shot from the gun: tansy tea. In fact, the biological spray has been used since the early days of the Colorado potato beetle invasion and continues to achieve notable success. Tansy is a common plant that thrives everywhere along the roadside. The trademark are the yellow cup-shaped flowers that appear from July to September. Their inner values, such as active tannins, lignans and essential oils, are not visible. This is how tansy tea is useful as an anti-potato beetle remedy:

    • Put 5 g of dried tansy in a cauldron
    • Add 1 liter of boiling water
    • stir and bring to a boil
    • Turn off the stove, put the lid on and let it steep for 15 minutes

    Fill the cooled tansy tea into a pressure sprayer. Wet potato and tomato plants with the spray as soon as you spot the first beetles or larvae. The effectiveness is increased by first pouring cold water over the tansy leaves, letting them steep for 24 hours and only then boiling them up.

    Regularly changing between the organic sprays is obligatory for optimal control success. Thanks to this strategy, you can counteract the development of resistance in the larvae. Ideally, the change always takes place when a new generation of Colorado potato beetles is about to start. If a neem spray was used in May, tansy tea should make life difficult for the beasts in July. A neem-containing product then meets the third generation in August.

    We don't outsmart the Colorado potato beetle. The pest has developed so many strategies against all kinds of toxins that in 100 years it will still be keeping us busy looking for effective means of control. (Prof. Dr. Stefan Kühne)

    Defense plants against Colorado potato beetle

    Nasturtium keeps Colorado potato beetles away

    Various defense plants provide you with green support in the fight against the potato beetle. By creating a bulwark of these plants around the potato or tomato bed, you optimize the control success of natural methods, home remedies and organic sprays. The following species scare off Colorado potato beetles with floral vitality:

    • Perennial flax (Linum perenne), growth height 30 cm, suitable for sunny locations with sandy, dry soil
    • Nasturtium (Tropaeolum), growth height 15-30 cm, much higher with climbing aids
    • Horseradish (Armoracia rusticana), growth height 30-50 cm, suitable for sun to partial shade with nutritious garden soil

    As a bed border or green fence, these types of plants exude special scents above and below ground, which throw the Colorado potato beetle that approaches. As a result of the irritation, the pests will avoid the garden as a precaution and look elsewhere for breeding sites. Scientific arguments do not support the defense against the pests. Since the perennials inspire with beautiful flowers, a test planting in the vegetable garden is definitely worthwhile.

    Preventing potato beetles - tips & tricks

    You can avoid confrontations with the Colorado potato beetle and its excessively greedy brood if you heed the following three tips. This is how you effectively prevent a plague in the potato bed:

    • digging up: Before planting seed potatoes, dig up the bed at least 50 cm deep
    • wet the ground: catch Colorado potato beetles crawling out of the ground with close-meshed protective nets
    • comply with crop rotation: Ideally, change the acreage annually, at the latest every 2 to 4 years

    The overwintering Colorado potato beetles have their sights set on preventive measures. By digging two spades deep into the vegetable patch in the spring, you can catch the hibernating pests and get rid of them. With close-meshed ground nets as a welcoming committee, you deprive the hungry beetles of the option of immediately attacking the tender little plants. Annual bed rotation keeps potato and other nightshade plants away from starving Colorado potato beetles crawling out of the soil. In addition, a crop rotation during the year makes sense. By planting other types of vegetables after the early potatoes, the development of a second generation of beetles is on shaky ground.

    frequently asked Questions

    Can potato beetles fly?

    Colorado potato beetles can fly very well

    With its 6 thin legs, a potato beetle can't walk very well. This handicap compensates for stable wings and an enduring condition. In fact, potato beetles are excellent fliers, easily moving from one garden to the next pasture. If a potato bed is crowded, Colorado potato beetles will take to the skies and look for new grazing grounds.

    What damage does the potato beetle cause?

    The Colorado potato beetle larva causes the greatest crop damage and not the adult beetle. Over the course of four developmental stages, the red larvae feed non-stop on the leaves of potato plants and other nightshade plants. It is not uncommon for entire fields and vegetable patches to be completely bare. Especially in the third and fourth larval stage, Colorado potato beetle larvae are veritable eating machines that only leave the skeleton of a plant.

    What does a potato beetle look like?

    A potato beetle is 7 to 15 mm long and has a roundish-oval, hairless body. Distinctive identification marks are two shiny, light yellow wing covers, each with 5 dark longitudinal stripes. Black spots can be seen on the yellow-orange pronotum. The beetle has 6 thin legs and two clearly visible antennae. The underside of the body is reddish brown. Males and females are visually indistinguishable for laypeople.

    Where does the potato beetle come from?

    The Colorado potato beetle is a leaf beetle and is a neophyte. This is what biologists call the animals that have been introduced from their homeland to other regions and have become at home there. Original origin is the state of Colorado in North America. This is what its middle name Colorado beetle refers to.

    Why don't Colorado potato beetles have natural enemies like most other pests?

    Basically, any Colorado potato beetle would be a welcome treat for birds or frogs. Of course, these beneficial insects give the Colorado beetle a wide berth because of the brightly colored warning clothing with the distinctive stripes. Likewise, the red larvae are consistently avoided by potential beneficial insects. In fact, the warning is justified, because Colorado potato beetles are armed with a slightly poisonous defense secretion.

    tips

    With a vital growth advantage, pre-germinated potatoes are well-armed for Colorado potato beetles and their insatiable larvae. The time window opens in mid-February for delicious early varieties such as "Cilena" or "Sieglinde". Egg cartons, fruit crates and multi-pot trays are well suited for propagation. In the bright, cool location at 12° to 15° Celsius, germination progresses quickly for planting out at the end of March/beginning of April.

Category:

Animals in the garden